The present invention relates to a separator for separating unhulled rice and unpolished rice from each other after hulling rice, and in particular, to such type of separator that rotationally shakes a circular separating vessel for the separation.
The inventor of the present invention has suggested in the Japanese Patent Application No. H11-106959 a rotary shaking separator which can reduce a space for installing the separator while maintaining separating accuracy of each of a plurality of circular separating vessels at a certain level even if they are arranged in multi-rows. To describe the configuration of this separator with reference to FIG. 13, the separator is designed to have a geometry in which a vertical supporting point xe2x80x9cOxe2x80x9d of an eccentric revolving motion is arranged above a shaft center of a rotary shaft 13 and an inclination line xe2x80x9cPxe2x80x9d is extended downwardly from said vertical supporting point xe2x80x9cOxe2x80x9d with a predetermined inclination angle, and a separating vessel 4A is rotatably mounted to an eccentric portion 22A, 23A formed on said inclination line xe2x80x9cPxe2x80x9d.
FIG. 14 is a schematic view illustrating said separating vessel 4A being revolved by the rotary shaft 13, and FIG. 15 is a schematic top view of the separating vessel 4A. Referring to FIGS. 14 and 15, the separating vessel 4A is supported by an eccentric portion xe2x80x9cHxe2x80x9d of the rotary shaft 13 inserted through a central portion xe2x80x9cSxe2x80x9d of the separating vessel 4A to allow the rotary shaft 13 to rotate with respect thereto, while a peripheral edge portion of the separating vessel 4A is supported by a plurality of springs xe2x80x9cBxe2x80x9d to prevent free rotation thereof (the separating vessel 4A is held and restrained at the central portion thereof by the rotary shaft 13 and at the peripheral edge portion thereof by the plurality of springs xe2x80x9cBxe2x80x9d respectively so that the motion of the separating vessel 4A is limited to a certain range). As the rotary shaft 13 rotates, the separating vessel 4A is revolved around the rotation center xe2x80x9cOxe2x80x9d of the rotary shaft 13 by an eccentricity amount xe2x80x9crxe2x80x9d (as shown by dotted lines 4A1, 4A2 and 4A3 in FIG. 15), and thereby unhulled rice and unpolished rice in the rice mixture are separated from each other on the separating vessel 4A so that the unhulled rice is discharged through a unhulled rice discharging port disposed in the vicinity of the central portion xe2x80x9cSxe2x80x9d and the unpolished rice is discharged through an unpolished rice discharging port disposed in the vicinity of the peripheral edge portion.
As for said separating vessel 4A, the rotary shaft 13 is designed to rotate under the condition that a center of gravity xe2x80x9cGxe2x80x9d of the separating vessel 4A is on the central portion xe2x80x9cSxe2x80x9d of the separating vessel 4A, but if supply of material to be separated is increased, the center of gravity is offset from the central portion xe2x80x9cSxe2x80x9d by the eccentricity amount xe2x80x9cxcex5xe2x80x9d, which may result in a failure in separation (G1 in FIG. 14). Furthermore, when stiffness of the springs xe2x80x9cBxe2x80x9d for preventing the free rotation of the separating vessel 4A gets weaker through a long-term service, a travelling distance of said materials placed on the separating plates of the separating vessel 4A to be separated thereby is possibly varied even along the same radii symmetrical to each other around the central portion xe2x80x9cSxe2x80x9d, resulting in a failure in separation at some locations in the same separating vessel 4A.
Yet further, because the rotary shaft 13 is inserted through the central portion xe2x80x9cSxe2x80x9d of the separating vessel 4A, the unhulled rice discharging port is necessarily designed to be narrow, which has exhibited some disadvantages that mounting of components is difficult, maintenance thereof is troublesome, and discharge of unhulled rice is not facilitated.
In the light of the problems described above, an object of the present invention is to provide a rotary shaking separator which prevents a failure in separation in the same separating vessel, allowing a constant separating accuracy to be maintained, without requiring a rotary shaft to be inserted through a central portion of the separating vessel.
To solve the problems described above, the present invention provides in the view of technology a rotary shaking separator comprising a separating vessel having a plurality of segmental separating plates arranged in a cone-shape form and a drive means for rotationally shaking said separating vessel so that once material to be separated, which is mixture composed of unhulled rice and unpolished rice, is supplied into a predetermined location of said separating vessel, said unhulled lice is discharged from a peripheral edge portion of said separating vessel and said unpolished rice is discharged from a central bottom portion of said separating vessel, wherein said separating vessel is supported by a plurality of drive means arranged in peripheral edge portions thereof on the same radii from the center of said separating vessel with arc lengths thereof being equal to one another, and said peripheral edge portions of said separating vessel are sequentially driven elliptically by said plurality of drive means to rotationally shake the whole of said separating vessel. Owing to this arrangement, since the mixture of unhulled rice and unpolished rice supplied into the separating vessel has greater acceleration in the vicinity of the peripheral portions, the unpolished rice having smaller grain size and greater specific gravity is carried toward the peripheral edge direction to be discharged from an unpolished rice discharging port, while the unhulled rice having greater grain size and smaller specific gravity slides down along the cone-shaped separating plates to be discharged from a central bottom portion of the separating vessel, thereby making it possible to retain a constant degree of separating accuracy without any failure in separation which might otherwise occur on the same separating plate and further to provide a rotary shaking separator which requires no rotary shaft inserted through the central portion of the separating vessel.
Further, it is preferable that the rotary shaking separator has a plurality of electric motors each being provided corresponding to each of a plurality of drive means. In this case, it is preferable that, in order to operate the plurality of electric motors synchronously, the apparatus comprises a measuring device for measuring a number of revolutions of a drive shaft of each of the electric motors and a controller for controlling every electric motor to be driven in a specific number of revolution based on the outputs from the measuring device as well as for actuating every electric motor synchronously with a specific phase delay therebetween, so that the drive means may be protected from being damaged by a possible over loading which might occur when the number of revolutions of each electric motor is varied or the phase thereof is shifted improperly.
Further, since a single electric motor may be used to actuate said plurality of drive means to eliminate any kinds of devices to operate a plurality of electric motors synchronously, the number of controllers and electric motors required for synchronous operation could be reduced, and thus a manufacturing cost could also be reduced.
When a plurality of electric motors are provided for a plurality of drive means so as to correspond one by one with each other, such type of drive means may be employed that comprises: an input shaft rotatably arranged vertically so as to transmit the revolution from an electric motor; a swash plate cam axially attached to said input shaft; and an output shaft which follows displacement caused by the revolution of said swash plate cam to make an elliptical locus. Further, another type of drive means may also be employed which comprises: an input shaft rotatably arranged vertically so as to transmit the revolution from an electric motor; a cam member having a swash plate cam attached thereto by inserting said input shaft therethrough; and an output shaft which is slidably moved on said swash plate cam driven by the revolution of said input shaft to make an elliptical locus by a displacement rotationally moving up and down. Yet further, another type of drive means may also be employed which comprises: an input shaft rotatably arranged obliquely so as to transmit the revolution from an electric motor; an eccentric shaft axially attached to said input shaft; a crank plate for converting a true circular motion of said eccentric shaft to an elliptical motion; and an output shaft axially attached to said crank plate for making an elliptical locus.
On the other hand, in the case where a single electric motor is used to actuate said plurality of drive means, such type of drive means may be employed that comprises: an input shaft rotatably arranged laterally so as to transmit the revolution from an electric motor; an intermediate shaft connected to said input shaft via a universal joint; and an eccentric shaft axially attached to said intermediate shaft.
Furthermore, said separating vessels arranged into multi-rows could enhance a separating ability in comparison with the separating vessel in single-row.
Still further, an apparatus according to the present invention further comprises: a circular dam disposed on a separating plate in a center of said separating vessel and having a unhulled rice discharging port; a shutter for opening or closing said unhulled rice discharging port; and a unit for actuating said shutter; wherein, said unit for actuating said shutter is actuated in response to an output signal from a unhulled rice/unpolished rice detection sensor for distinguishing the unhulled rice and unpolished rice from each other on the separating plates, so that a discharge amount of the unhulled rice could be controlled based on a proportion of the unhulled rice layer to the unpolished rice layer on the cone-shaped separating plates during a period from the beginning of separation throughout the separating operation.
Yet further, since each of said separating plates of said separating vessel is constructed such that an inclination angle thereof is allowed to be regulated respectively and said apparatus further comprises a regulator unit for regulating the inclination angle of said separating plates, the inclination angle or a slope of he separating plate of the separating vessel can be adjusted, so that a thickness of the layer of rice mixture on the separating plates can be controlled appropriately.
Besides, since the apparatus according to the present invention further comprises a level sensor for detecting a level of a layer thickness of rice mixture on said separating plates so that when said level sensor detects the thickness of the layer of said rice mixture being over or under a predetermined level, said regulator unit is actuated to regulate the inclination angle of the separating plates toward a gentle slope direction or a steep slope direction, the rice mixture can be distributed over the separating plates with the level in layer thickness being higher in the central side gradually getting lower toward the peripheral edge side thus to reduce a possible risk that the unhulled rice is discharged by centrifugal force through the unpolished rice discharging port.